NUL byte disallowed in arguments

[mmhat]

The following program worked just fine when compiled with GHC <9.8:

module Main (main) where

import System.Process

main :: IO ()
main = callProcess "echo" ["foo\0bar"]

Compiled with GHC >=9.8 it outputs the following runtime error:

*** Exception: /usr/bin/echo: checkForInteriorNuls: invalid argument (FilePaths must not contain internal NUL code units.)

The reason is that process also treats the arguments as FilePath:

process/System/Process/Posix.hs

Line 139 in d74bba2

withMany withFilePath (cmd:args) $ \cstrs ->

(Linking to the POSIX implementation here since I am running Linux.)
The System.Posix.Internals.withFilePath function referenced there checks for internal NULL characters since base >4.19 due to the accepted CLC propsal haskell/core-libraries-committee#144.

[mmhat]

The Windows implementation uses Foreign.C.String.withCWString which seems the correct choice to me.